This invention relates to the field of secondary or rechargeable electrical battery cells of the alkali metal and halogen reactants type, such cells being commonly operated at elevated cell temperatures.
Electrical battery cell capabilities are a limiting consideration in a number of modern day technical arts. In the transportation industry, for example, the frequently discussed electrically powered automobile has failed to become a practical reality principally because of propulsion energy storing or battery limitations. From another perspective of this difficulty, the commonly used lead acid battery cell is frequently credited with an energy storage density in the range of 10 to 15 watt-hours per pound, a density which is found to be inadequate for satisfactory use in even runabout or local delivery battery powered automobile service.
In the fields of aircraft and spacecraft design, energy storage limitations directly affect the payload and propulsion requirements of flight vehicles and therefore are of intense concern. The first space satellite, for example, used nickel/cadmium batteries that displayed an energy density capability of one to two watt-hours per pound of battery weight. In the ensuing twenty years of space research, the energy density of such nickel/cadmium and related cells has increased to densities in the range of six to twelve watt-hours per pound of battery weight. At this point of battery cell development, the nickel/hydrogen battery cell became available and is currently the state of the art cell for spacecraft applications. The nickel/hydrogen cell achieves energy densities in the range of 15 to 20 watt-hours per pound. Present expectations are, however, that batteries employing an alkali metal and halogen or other reactant will provide the next generation of battery technology for spacecraft usage. The presently investigated sodium and sulfur cell embodiment of this technology is, for example, capable of providing energy densities approaching 50 watt-hours per pound of battery weight.
The alkali metal and halide battery cell as is principally described herein is capable of providing even greater energy densities, densities in the range of 100 watt-hours per pound when embodied in the form of a sodium and sulfuryl chloride reactant cell. Heretofore, however, there have been difficulties in achieving secondary cell or rechargeable cell characteristics in the alkali metal and halide reactant battery cell and especially in achieving this secondary cell capability in the sodium and sulfuryl chloride cell.
The sodium and sulfuryl chloride version of the alkali metal metal halide cell has received considerable attention in the patent art as is illustrated, for example, by the patents of G. E. Blomgren et al, U.S. Pat. No. 4,400,453 and several patents to G. C. Farrington and P. C. Lord at General Electric Company, including U.S. Pat. No. 3,879,221; U.S. Pat. No. 3,879,222; U.S. Pat. No. 3,879,223 and U.S. Pat. No. 3,879,224.
Notwithstanding this inventive attention, the prior art has failed to provide a satisfactory secondary or rechargeable alkali metal and halide or sodium and sulfuryl chloride battery cell.